## Reflection: Developing a Conceptual Understanding Exploring Circumference - Section 4: Exploring Circumference

Students had to work together to measure the diameter and the circumference of each object.   When we came back together, students shared out their data from their table and graph.  I had students participate in a Think Pair Share about the relationship they saw between the diameter and the circumference of each circle.  Students were able to see that if they multiplied the diameter by three they got close to the circumference.

Later in the lesson, I dramatically revealed the formula for circumference, C = pi times diameter.  I asked the students why this made sense and they were able to make the connection that pi is close to 3.  Many students had an audible “ah-ha” moment.  Then I asked why the formula C = 2 times pi times radius can also be used.  Students were able to share that they were equivalent because if you double the radius, you get the diameter.  This lesson paid off because students were able to connect with the formulas and work to understand what they are and why they work.

Developing a Conceptual Understanding: Developing A Conceptual Understanding of Circumference

# Exploring Circumference

Unit 8: Geometry
Lesson 5 of 19

## Big Idea: What is pi, anyway? Students explore the relationship between circumference and diameter by measuring a variety of circles and use it to derive the formula for circumference.

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50 minutes

### Andrea Palmer

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